730 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
larger ones; about 16 costellae occupy a space of 5 mm. at the front of a valve 
about 6 mm. long. 
Pedicle valve flat to slightly concave in lateral profile ; beak slightly projecting 
posterior to the posterior margin; umbo narrow, slightly swollen and produced 
forward as a narrow, low fold which may or may not disappear at about the mid- 
dle of the valve. Anteromedian portion anteriorly depressed to form a shallow, 
wide sulcus. Area bounding sulcus slightly folded; lateral areas nearly flat to 
concave. Interarea moderately long, apsacline. 
Brachial valve with sulcate umbo; sulcus extending nearly to middle of valve; 
anteromedian half of valve undulated into a broad fold; lateral areas slightly 
convex and with steepening slopes toward the margins. Area in front of cardinal 
extremities sulcate. Interarea moderately long but shorter than the interarea of 
the pedicle valve, hypercline. 
Interior of pedicle valve well thickened; delthyrial cavity small, choked with 
excess shell at the apex; ridges between pallial impressions thick; surface cov- 
ered by small granules. 
Interior of brachial valve with paired septa extending nearly to the front mar- 
gin but with the crests of the septa at about the middle of the valve ; adductor field 
small, surrounded posterolaterally by narrow ridges. Radial thickenings between 
pallial impressions moderately strong. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness 
Eiolotypels «iced... 2: 7.8 6.6 12.8 14.8 2.2 
Paratype (FL7370D ) hes. « tier ened 6% 7.0 5.9 10.0 12.3 28 
vi CPIOQOOA) ethane sacn ne 7.4 6.7 11.2 14.1-+ 2.4 
Types.—Holotype: 117376a; figured paratypes: 110908a,b-d,g,h, rI10goga, 
I1ogiia,d, 110912, 117375, 117376c-f,k,1; unfigured paratypes: 110908e,f, 
11ogogb, 11091Ib,c, 117376b,g-j,m,n. 
Horizon and locality——Arline formation in Tennessee: 100 yards southwest 
of the Negro Cemetery, 4 mile northeast of center of Friendsville; glade 4+ mile 
southeast of Friendsville, Concord (T.V.A. 138-SW) Quadrangle; 1,500 feet 
south of Burnett Creek, Shooks Gap (T.V.A. 137-NE) Quadrangle. 
Arline formation in Virginia: Near entrance to Porterfield Quarry, 5 miles 
east of Saltville, Maccrady (T.V.A. 218-NW) Quadrangle. 
Little Oak formation in Alabama: At junction Bailey Gap road and Cahaba 
Valley road, SWiSW3 sec. 13, T. 19 S., R. 2 W., 13 miles northeast of New- 
hope Church, Vandiver (15’) Quadrangle. 
Discussion.—This species is characterized by its great width along the hinge 
as compared to its length. Furthermore, the cardinal extremities are acutely an- 
gular even in the adult form, thus differing from J. biseptatum. From I. ricevil- 
lense this species differs in its more acute cardinal extremities, greater width, and 
less even character to the costellae. 
